The 1958 model year signaled a major change of direction for America’s most popular car. The little Stovebolt Chevy was all grown up.

We can’t really say that Chevrolet moved upmarket in 1958, but it definitely moved uptown. While the bow-tie brand continued as the General Motors volume leader, secure on the lowest rung of the carmaker’s product-price ladder, the Chevy line received a glamorous makeover. The little Stovebolt had grown up.

The ’58 Chevy was longer—2.5 inches in wheelbase and 9 inches overall—and wider, lower, and more than 300 lbs heavier than in the previous year. All-new sheet metal from Harley Earl’s GM design studios emphasized the greater size and weight.  A new X-frame chassis rode on coil springs at all four corners, and there was a new, bigger 348 cubic-inch V8 available. And there was a brand new flagship at the top of the Chevy lineup for ’58 called the Impala—a model name that would continue to this day.

The Impala’s rollout in October of 1957 was modest, maybe a bit tentative. The Impala was merely part of the Bel Air line that first year, and there were but two body styles: Sport Coupe and Convertible. (In the following year, Impala became a stand-alone line with a full range of body styles.) The Impala name itself, honoring the speedy and graceful African antelope, had originated at Chevrolet on a five-place Motorama dream car, the 1956 Corvette Impala (read about it here).

Like the rest of the ’58 Chevrolet line, the Impala sported trendy quad headlamps in front, but it distinguished itself from the Biscayne and Bel Air junior models with six round tail lamps at the rear instead of four—an Impala custom that would continue for years. Both the Impala Sport Coupe and Convertible wore stylized, non-functioning chrome air vents on their rear quarter panels, while the hardtop also received a similar bright-metal  piece at the trailing edge of the roof panel, called a “roof scallop” in Chevy lingo. What’s more, the Impala used different quarter panels, deck lid, and roof panel than the rest of the full-sized Chevrolets.

Inside, the Impala was a significant deviation from previous Chevrolets, known mostly for their quiet conservatism. Now there were bold, bright colors and materials, deluxe appointments, and a full range of extra-cost luxury options, from power windows to air conditioning to signal-seeking radio. Memorable Impala cabin features included a racy six-hole steering wheel and the speaker grille built into the center of the rear seat. The teenagers who swooned at these little details are now senior citizens, but they still remember.

With its big-car styling, flashy deluxe interiors, and full line of comfort and convenience features, both standard and optional, the Impala signaled a major departure for Chevrolet, blurring the distinctions between the apple-pie brand and GM’s senior divisions. For better or worse, buyers could now own a car approaching Pontiac, Olds, or Buick style, but at Chevrolet prices. Whether that was a good move or a bad one for General Motors way back in 1958 is an open question. But it sure worked for Chevrolet: There’s an Impala in the lineup to this day.